1. Technical Field
The present invention relates to a single focus optical image capturing system. More particularly, the present invention relates to a compact single focus optical image capturing system applicable to electronic products.
2. Description of Related Art
In recent years, with the popularity of mobile products with camera functionalities, the demand of optical lens systems is increasing. The sensor of a conventional photographing camera is typically a CCD (Charge-Coupled Device) or a CMOS (Complementary Metal-Oxide-Semiconductor) sensor. As the advanced semiconductor manufacturing technologies have allowed the pixel size of sensors to be reduced and compact optical lens systems have gradually evolved toward the field of higher megapixels, there is an increasing demand for compact optical lens systems featuring better image quality.
In an optical lens system, a TV distortion doesn't affect the image clarity but causes the image shape distortion. The TV distortion of a conventional fixed-focus camera is usually maintained within 3%. When the TV distortion is greater than 3%, it will be apparent to human eyes. However, the level of difficulty for maintaining the TV distortion increases with the size of the image. Furthermore, when a conventional fixed-focus camera is employed for both close-up photographing and long distance photographing, the conventional fixed-focus camera can not offer the desired TV distortion for both close-up photographing and long distance photographing.
The TV distortion condition of a conventional single focus camera is commonly designed for satisfying long distance photographing such as the one disclosed in U.S. Pat. No. 8,000,031, as a result, a high TV distortion is generated for close-up photographing. The demand for close-up photographing increases rapidly nowadays, the aforementioned single focus camera no longer satisfies consumers. The TV distortion condition should be designed for satisfying both close-up photographing and long distance photographing, thus high image quality can be obtained for both close-up photographing and long distance photographing.